1824 - South Pass discovered

South Pass opened the overland trail to the western slopes of the Rockies and the open country beyond.

Thomas Fitzpatrick, Jim Bridger, Jedidiah
Smith, and Etienne Provost (Provo, Utah named in his honor),
discover South Pass through the Rocky Mountains. South Pass
was an essential course through the mountains that made it possible
for Fitzpatrick to blaze open the Oregon Trail in 1836.